Help please! Rusty brown spots, then yellowing, please help!

Ok, you guys were such a big help the last time i had a problem, so here goes this time. Every plant seems to have at least 1 (most have 2) of these leaves. They start with rusty brown spots down the center of the leaf, after a day or two they turn yellow and fall off a few days after that. Otherwise the plants are doing great.

400w hps
hydro in rockwool
5.8-6.0 H2O PH
2 1/2 weeks into veg

thank you guys in advance, me

Your stems are also purple. Purple stems and clawed down leaves generally indicates you're suffocating her with water. The yellowing and brown spots can be a combination of nitrogen and micro nutrient deficiency, particularly zinc I would think, but that's just a mildly educated guess. You can make more zinc available to your plant by adjusting your PH to something closer to 6.8-7. You can also invest in an efficient foliar spray called spray-n-grow that feeds a cocktail of essential micro nutrients to your plant through the leaves.